class Download

class Download extends FileProcessBase implements ContainerFactoryPluginInterface {
    
    /**
     * The file system service.
     *
     * @var \Drupal\Core\File\FileSystemInterface
     */
    protected $fileSystem;
    
    /**
     * The Guzzle HTTP Client service.
     *
     * @var \GuzzleHttp\Client
     */
    protected $httpClient;
    
    /**
     * Constructs a download process plugin.
     *
     * @param array $configuration
     *   The plugin configuration.
     * @param string $plugin_id
     *   The plugin ID.
     * @param array $plugin_definition
     *   The plugin definition.
     * @param \Drupal\Core\File\FileSystemInterface $file_system
     *   The file system service.
     * @param \GuzzleHttp\ClientInterface $http_client
     *   The HTTP client.
     */
    public function __construct(array $configuration, $plugin_id, array $plugin_definition, FileSystemInterface $file_system, ClientInterface $http_client) {
        $configuration += [
            'guzzle_options' => [],
        ];
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->fileSystem = $file_system;
        $this->httpClient = $http_client;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('file_system'), $container->get('http_client'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
        // If we're stubbing a file entity, return a uri of NULL so it will get
        // stubbed by the general process.
        if ($row->isStub()) {
            return NULL;
        }
        [
            $source,
            $destination,
        ] = $value;
        // Modify the destination filename if necessary.
        $final_destination = $this->fileSystem
            ->getDestinationFilename($destination, $this->configuration['file_exists']);
        // Reuse if file exists.
        if (!$final_destination) {
            return $destination;
        }
        // Try opening the file first, to avoid calling prepareDirectory()
        // unnecessarily. We're suppressing fopen() errors because we want to try
        // to prepare the directory before we give up and fail.
        $destination_stream = @fopen($final_destination, 'w');
        if (!$destination_stream) {
            // If fopen didn't work, make sure there's a writable directory in place.
            $dir = $this->fileSystem
                ->dirname($final_destination);
            if (!$this->fileSystem
                ->prepareDirectory($dir, FileSystemInterface::CREATE_DIRECTORY | FileSystemInterface::MODIFY_PERMISSIONS)) {
                throw new MigrateException("Could not create or write to directory '{$dir}'");
            }
            // Let's try that fopen again.
            $destination_stream = @fopen($final_destination, 'w');
            if (!$destination_stream) {
                throw new MigrateException("Could not write to file '{$final_destination}'");
            }
        }
        // Stream the request body directly to the final destination stream.
        $this->configuration['guzzle_options']['sink'] = $destination_stream;
        try {
            // Make the request. Guzzle throws an exception for anything but 200.
            $this->httpClient
                ->get($source, $this->configuration['guzzle_options']);
        } catch (\Exception $e) {
            throw new MigrateException("{$e->getMessage()} ({$source})");
        }
        if (is_resource($destination_stream)) {
            fclose($destination_stream);
        }
        return $final_destination;
    }

}